1. Field of the Invention
The present invention relates to a pallet changer used for changing work pallets to be fed onto a machine tool, such as a machining center, and more particularly, to a hand-operated pallet changer.
2. Description of the Related Arts
Generally, a machine tool, such as machining center, has a pallet mounting portion provided with a clamping device for locating and clamping a work pallet on the mounting portion. The work pallet is designed so that a work piece can be secured thereon. A work pallet located on the mounting portion of the machine tool must be changed efficiently for a new one after the machining of the work piece on the work pallet located on the mounting portion of the machine tool is finished, and the work piece secured on the work pallet must be changed for a new one after the work pallet is removed from the mounting portion of the machine tool.
Recently, a pallet changer has been used for the above-mentioned changing operation of the work pallets. A conventional pallet changer is generally designed to automatically change the work pallet, located on the mounting portion of the machine tool, by actuators driven by a hydraulic, pneumatic or electric power source, and accordingly, can dispence with unnecessary labor for the changing operation of the work pallets. However, such an automatic pallet changer is expensive and is difficult to maintain and further, when such an automatic pallet changer is installed, additional electric wiring must be provided. Furthermore, such an automatic work pallet changer requires an additional space for the installation of a hydraulic, pneumatic or electric power unit. Therefore, in a relatively small-scale plant, it often becomes difficult to install the automatic pallet changer with a power unit after a machine tool has been installed, due to restrictions in installation space.